'''编写程序,检查字符串"Life is short.I use python"中是否包含字符串"python"
   若包含则替换为"Python"后输出新的字符串,否则输出原字符串'''
str = 'Life is short.I use python'
key_word = 'python'
if key_word in str:
    str = str.replace(key_word,'Python')
    print(str)
else:
    print(str)
